Non-irrigated Control Research Articles

Interactive effects of deficit irrigation and shoot and cluster thinning on grapevine cv. Tempranillo. Water relations, vine performance and berry and wine composition

The effects of crop level and irrigation on water relations, yield, grape and wine composition were studied during two seasons in a Tempranillo vineyard in Spain. Irrigation was applied at two levels: R2 (with mild deficit irrigation applied during all the season) and R1 (with more severe water stress applied before veraison). Deficit irrigated vines were compared to a non-irrigated control. Crop levels imposed resulted in 11, 20, and 27 clusters per vine. Over all treatments, yield and ratio of leaf area to yield (LA: Y) were different between years: 4.4 and 16.3 t ha−1 and 1.72 and 0.88 m2 kg−1 in 2005 and 2006, respectively. In 2005, large differences in grape and wine composition occurred among non-irrigated and the irrigated treatments, but not between R1 and R2 treatments. Wines from non-irrigated vines were more acid, had higher total anthocyanins, and higher color intensity. In 2006, irrigation had less effect on grape and wine variables. The effect of shoot and cluster thinning on wine composition was different between seasons due to the different crop load values between years. Grape composition was negatively affected by high crop level only for values of LA: Y lower than 1.5 m2 kg−1.

Effects of long-term irrigation with treated wastewater. Part II: Role of organic carbon on Cu, Pb and Cr behaviour

Abstract The long-term impact of irrigation on a Mediterranean sandy soil irrigated with treated wastewater (TWW) since 1980 was evaluated. The main soil properties (CEC, pH, size distribution, exchangeable cations and chloride, hydraulic conductivity) as well as the organic matter and Cu, Cr and Pb speciation in an irrigated soil and a non-irrigated control soil at various soil depths were monitored and compared during a 2 year experiment. In this second part, we focused on Cu, Cr and Pb behaviour in relation with soil organic carbon (SOC). Soil samples were collected every 3 months during 2 years at the depths 0–20, 20–40 and 40–60 cm and were analysed for exchangeable and total metals, organic carbon content, metal sequential extraction and humic substances – Humic Acids (HA), Fulvic Acids (FA) and Non-Humified Fraction (NHF). Long-term irrigation with a domestic treated wastewater (TWW) may be considered safe with regard to trace metal accumulation in soil. Irrigation lowered the HA and NHF fractions of SOC and made the FA fraction more mobile. Cu bound preferentially to the SOC fraction, Cr was found mainly in the reducible fraction and Pb was bound to all fractions indiscriminately. Cu exhibited a high affinity for the HA fraction, while Pb and Cr had a high affinity for the FA fraction, which indicates a greater mobility of the organically-bound Pb and Cr than of the organically-bound Cu. Evaluation of the potential metal mobility has to take into account not only the usual speciation between labile, reducible and oxidisable fractions, but also the nature of the SOC responsible for the oxidisable fraction.

Effects of long-term irrigation with treated wastewater. Part I: Evolution of soil physico-chemical properties

Abstract The long-term impact of irrigation on a Mediterranean sandy soil irrigated with Treated wastewater (TWW) since 1980 was evaluated. The main soil properties (CEC, pH, size distribution, exchangeable cations and chloride, hydraulic conductivity) as well as the organic matter and Cu, Cr and Pb speciation in an irrigated soil and a non-irrigated control soil at various soil depths were monitored and compared during a 2 years experiment. In this first part, the evolution of the physico-chemical soil properties was described. The irrigation with TWW was beneficial with regard to water and nutrient supplying. All the exchangeable cations other than K + were higher in the irrigated soil than in the reference one. A part of the exchangeable cations was not fixed on the exchange complex but stored as labile salts or in concentrated soil solution. Despite the very sandy soil texture, both saturated and unsaturated hydraulic conductivity exhibited a significant diminution in the irrigated soil, but remained high enough to allow water percolation during rainy periods and subsequent leaching of accumulated salts, preventing soil salinization. In the irrigated soil, exchangeable sodium percentage (ESP) exhibited high values (20% on average) and the soil organic C was lower than in the reference. No significant effect was noticed on soil mineralogical composition due to irrigation.

Adubação para primeiro ano pós-plantio (N e K2O) de cafeeiros fertirrigados na região sul de Minas Gerais

Irrigated coffee production represents approximately 10% of the total area planted with coffee and 25% of Brazil's annual production of the crop. This study aimed at determining the effects of different doses and splittings of N and K 2 O fertilization, applied via drip fertirrigation, on growth and leaf N and K concentrations in the first year of fertilization after planting. The cultivar Catigua MG-3 was used in a 2.50 m x 0.6 m spacing. Treatments consisted of combinations of five doses of N and K 2 O fertilizer ((i) 70%, (ii) 100%, (iii) 130%, (iv)160%, and (v) 190% of the recommended dose for non-irrigated coffee), two split applications ((i) four and (ii) twelve applications) and a non-irrigated control treatment that received 100% of the recommended dose in four applications during the rainy season. The experimental design was in randomized blocks with four replications in split-plots. Plots were constituted by different splitting managements and split-plots by different doses. In each split-plot eight plants, from a total of ten, were sampled. Plant growth (plant height, stem and crown diameter) was higher in the treatments that received twelve fertilizer applications and did not vary according to the fertirrigation doses, but was lower in the non-irrigated control treatment. In fertirrigated coffee fields in the southern region of Minas Gerais state, N and K 2 O doses should be reduced to 70% of the amount usually recommended for non-irrigated coffee, providing that twelve monthly applications are done.

Impact of Sprinkler Irrigation Amount on Peanut Quality Parameters

Abstract Peanut quality parameters were analyzed across four irrigation levels during the 2002 through 2007 crop years. The peanut quality parameters consisted of total sound mature kernels and sound splits (farmer stock grade), shelling outturn by commercial edible size, accept and reject kernels by commercial edible size, seed germination, and aflatoxin. The four irrigation levels consisted of a full level (100%), two reduced levels (66% and 33%), and a non-irrigated control. The research was conducted at the USDA/ARS National Peanut Research Laboratory's Multi-crop Irrigation Research Farm in Shellman, Georgia. By year, significant differences in the irrigation treatments depended upon precipitation distribution for the specific quality parameters. For the average over the six years in the study, farmer stock grade was not significantly different in the 100, 66, and 33% treatments while all were significantly higher than the non-irrigated control. Total shelling outturn and total edible outturn were higher in the 100 and 66% compared to the 33% and non-irrigated treatments. Total reject outturn and total oil stock were not significantly different in the 100, 66, and 33% treatments, while all were significantly lower than the non-irrigated control. Percent seed germination did not differ across treatments. Aflatoxin in total reject outturn and total oil stock was significantly higher for the non-irrigated treatment compared to the irrigated treatments.

Effects of treated wastewater irrigation on soil salinity and sodicity in Sfax (Tunisia): A case study

In arid regions such as near Sfax (Tunisia), treated wastewater effluents (TWE) are often applied as agricultural irrigation. Irrigation TWE usually contain large amounts of carbon, nitrogen and sodium. The objective of this study was to evaluate the impact of TWE irrigation on soil salinity and sodicity. In the city of Sfax, two sites were selected with two soil types (fluvisol and calcisol) having been irrigated for 4 and 15 years respectively. Soils were sampled at three different depths (0-30, 30-60 and 60-90 cm) in the TWE irrigated area and in a non-irrigated control area. Irrigated and non-irrigated study soils were analyzed for pH, nitrate and ammonia, electrical conductivity (ECs), exchangeable sodium percentage (ESP), sodium absorption ratio (SAR) and soil organic matter. The fluvisol, irrigated for only four years, is more affected by salinity than the calcisol irrigated for 15 years. In the upper fluvisol layer irrigated by the treated wastewater, ECs reach 8 mS•cm-1 and ESP a value of 15% while in all layers of the calcisol, ECs and ESP are lower and rarely exceed 4 mS•cm-1 and 6% respectively. This result is due to a combination of factors in the fluvisol treatment area including texture, cation exchange capacity, irrigation procedure and crop management.

Photosynthesis, yield, and chemical composition of Tieguanyin tea plants (Camellia sinensis (L.) O. Kuntze) in response to irrigation treatments

Abstract Tieguanyin Oolong tea (Camellia sinensis (L.) O. Kuntze) is a name brand important commodity for Anxi county, Fujian province in China. Four-year-old tea plants at a tea plantation in Anxi were subjected to six different irrigation treatments (i.e. 5, 10, 15, 20, and 25 d irrigation intervals for T1 to T5 with a rate of 3.5 kg water per plant, plus a non-irrigated control). After 50 d of irrigation treatments, leaf water potential was −1.70, −2.34, −2.48, −2.89, −3.55, and −4.92 MPa for treatment T1, T2, T3, T4, T5, and control, respectively. Leaf biomass yield increased by 32.8%, 21.9%, and 21.3% for T1, T2, and T3, respectively, compared to control. The net photosynthesis (Pn), stomatal conductance (gs) and transpiration (E) decreased with irrigation interval increasing. Tea polyphenol (TP) and free amino acid (AA) decreased when the irrigation intervals were increased, but caffeine (CA) content apparently increased as the irrigation intervals were increased. To balance irrigation water demand and tea yield and quality, it is recommended that the irrigation interval should be set at 10 d with a rate of 3.5 kg water per plant for the optimal production in Anxi, Fujian province of China.

Elevated carbon dioxide alters impacts of precipitation pulses on ecosystem photosynthesis and respiration in a semi-arid grassland

Predicting net C balance under future global change scenarios requires a comprehensive understanding of how ecosystem photosynthesis (gross primary production; GPP) and respiration (Re) respond to elevated atmospheric [CO(2)] and altered water availability. We measured net ecosystem exchange of CO(2) (NEE), GPP and Re under ambient and elevated [CO(2)] in a northern mixed-grass prairie (Wyoming, USA) during dry intervals and in response to simulated precipitation pulse events. Elevated [CO(2)] resulted in higher rates of both GPP and Re across the 2006 growing season, and the balance of these two fluxes (NEE) accounted for cumulative growing season C uptake (-14.4 +/- 8.3 g C m(-2)). Despite lower GPP and Re, experimental plots under ambient [CO(2)] had greater cumulative uptake (-36.2 +/- 8.2 g C m(-2)) than plots under elevated [CO(2)]. Non-irrigated control plots received 50% of average precipitation during the drought of 2006, and had near-zero NEE (1.9 +/- 6.4 g C m(-2)) for the growing season. Elevated [CO(2)] extended the magnitude and duration of pulse-related increases in GPP, resulting in a significant [CO(2)] treatment by pulse day interaction, demonstrating the potential for elevated [CO(2)] to increase the capacity of this ecosystem to respond to late-season precipitation. However, stimulation of Re throughout the growing season under elevated [CO(2)] reduced net C uptake compared to plots under ambient [CO(2)]. These results indicate that although elevated [CO(2)] stimulates gross rates of ecosystem C fluxes, it does not necessarily enhance net C uptake, and that C cycle responses in semi-arid grasslands are likely to be more sensitive to changes in precipitation than atmospheric [CO(2)].

Subsurface Drip and Overhead Irrigation: A Comparison of Plant Boll Distribution in Upland Cotton

Although subsurface drip (SSD) is used as a water‐efficient alternative to overhead irrigation in many crops, the effects of SSD on the distribution of bolls on cotton plants (Gossypium hirsutum L.) have not been thoroughly examined. The purpose of this study was to add to the current knowledge about the effects of SSD on cotton yield dynamics. Cultivar DP 488 BG/RR was grown in three studies during 2 yr with irrigation treatments consisting of overhead irrigation (Overhead), a nonirrigated control (Nonirrigated), SSD matched to overhead irrigation amounts and frequency (SSD Matched), and SSD based on soil moisture (SSD Fed) irrigated cotton. The cotton was grown in two locations in 2004 and one location in 2005 in Georgia. Crop height, maturity, and soil moisture status were monitored throughout the growing season in each location. At harvest, a subplot consisting of one harvest row measuring 3 m in length was removed from each plot and handpicked to determine cotton boll distribution in each plot. Irrigation method had a significant impact on boll distribution on the plants, with the overhead irrigation treatment consistently having less cotton near the bottom of the plant and more cotton near the top than either of the SSD methods. We conclude that SSD irrigation decreases early‐season fruit loss, resulting in heavier carbohydrate sinks and decreasing overall growth and upper boll filling on the crop.

EFFECT OF A DEFICIT IRRIGATION REGIME ON THE QUALITY OF WINES MADE FROM WHITE GRAPES (VITIS VINIFERA L.) GROWN IN SEMIARID AREAS

ABSTRACT The dependence of wine quality on the irrigation management strategies in Vitis vinifera L. was tested from 1999 to 2002. A drip‐irrigation experiment was performed on white grapes of the cultivars Baladí, Airén, Montepila, Muscat Blanc à Petits Grains and Pedro Ximénez, grafted and vineyard‐planted in 1995 in Cabra (Cordoba, Spain). Treatments consisted of a nonirrigated control and an experimental deficit irrigation, in which water was applied from fruit set until near harvest. A total of 19 analytical parameters were measured, including alcohols, total phenol content and optical density as well as ethanol, pH, total acidity and dry extract. Wines were evaluated for their visual characteristics, aroma, taste and finish. The irrigation treatment contributed to a higher dry extract, and an increase in malic acid and potassium in wines. There was a decrease in pH, isobutanol and isoamyl alcohols with increasing water application. Sensory evaluation ranked irrigated over nonirrigated wines with the only exception of the wines of Muscat Blanc à Petits Grains. The main defects of nonirrigated wines were attributed to visual characteristics and poorer taste quality.PRACTICAL APPLICATIONSProper irrigation management, i.e., optimizing both the timing and the amount of water supplied, plays a significant role in wine quality and is especially important in arid and semiarid areas. The aim of this study was to ascertain the effect of irrigation in wine quality. In this study, irrigation was applied only during periods in which water stress might affect production and harvest quality. The chemical results ranked irrigated over nonirrigated wines and Muscat Blanc à Petits Grains over other cultivars, regarding their quality. Sensory evaluation ranked irrigated over nonirrigated wines with the only exception of the wines of Muscat Blanc à Petits Grains. Therefore, deficit irrigation during berry development and ripening appears to be a promising technique for the production of quality young wines in semiarid achieving a compromise between aroma and taste quality.

Physiological and productive responses of Olea europaea L. cultivars Frantoio and Leccino to a regulated deficit irrigation regime

Olive is a drought-tolerant species and it is known that it responds efficiently to any additional water up to a limit. A field experiment was planned with the following aims: to provide estimates of crop evapotranspiration (ETc) to improve water use efficiency during the growing season; to present guidelines for efficient management of irrigation scheduling; and to characterize the relationship between plant water status and optimum fruit yield. These relationships were monitored during four years by analysing the influence of deficit irrigation strategies on mature modern-trained olive trees of cultivars Frantoio and Leccino. Treatments were a non-irrigated control (rain-fed) and three treatments that received a seasonal water amount equivalent to 33, 66 and 100% of ETc, from the beginning of pit hardening to early fruit veraison. Results of the relationship between leaf water potential and maximum stomatal conductance (Ψpd vs. g smax) showed that the stomatal apparatus in Frantoio was more sensitive to water deficit than that of Leccino. Differences in yield between treatments were mainly related to mean fruit weight, indicating that water availability might have affected growing conditions before flowering or during the early stages of fruit growth rather than later in the summer season. Vegetative development was a function of water available to plants. Frantoio achieved the highest crop production per unit of water consumption. Oil quality was scarcely affected by deficit irrigation. Regulated deficit irrigation of olive trees after pit hardening could be recommended, at least under the experimental conditions of this study. Given the different long-term watering response of Frantoio and Leccino, a cultivar-specific irrigation scheduling is advisable.

Irrigation Scheduling for ‘Sovereign Coronation’ Table Grapes Based on Evapotranspiration Calculations and Crop Coefficients

Several irrigation treatments were evaluated on ‘Sovereign Coronation’ (Vitis labruscana) table grapes at two vineyard sites in Ontario, Canada in 2003 to 2005 to assess the usefulness of the Food and Agriculture Organization of the United Nations Penman-Monteith equation for predicting vine irrigation needs. Data (relative humidity, wind speed, solar radiation, and temperature) for calculating reference evapotranspiration (ETo) were downloaded from the Ontario Weather Network. The five irrigation treatments were nonirrigated control plus four based on combinations of one of two ETo values [100% (ET100) or 150% (ET150)] and two crop coefficients [Kc (fixed at 0.75 or 0.5–0.8 based upon increasing canopy volume)] used to calculate the required irrigation water volume. Transpiration (Ts), leaf water potential (ψ), and soil moisture data were collected in all three seasons. Yield components data were collected and berries were analyzed for soluble solids, pH, titratable acidity (TA), anthocyanins, methyl anthranilate (MA), and total volatile esters (TVE). Irrigation typically increased Ts rate and soil moisture; the nonirrigated treatment showed consistently lower Ts and soil moisture over the three seasons. Irrigation also increased leaf ψ, which was lower throughout the three seasons for nonirrigated vines. Irrigation additionally increased yield and its various components (clusters per vine, cluster weight, and berries per cluster) in 2005. Berry weights were higher for irrigated treatments at both sites, and were consistently the main variable leading to yield increases. Soluble solids was highest for the Kc = 0.75 treatments. pH, TA, anthocyanins, and phenols were highest in nonirrigated treatments in 2003 and 2004, but were highest in irrigated treatments in 2005. MA and TVE were highest in the ET150 treatments. The use of irrigation was effective in reducing water stress and for improving yield and fruit composition of ‘Sovereign Coronation’ table grapes in the Niagara region of Ontario. The ET150 treatments were particularly beneficial. Soil and vine water status measurements indicated that irrigation was required for Summer 2003 and 2005 due to dry conditions.

Irrigation Scheduling for ‘Sovereign Coronation’ Table Grapes Based on Evapotranspiration Calculations and Crop Coefficients

Several irrigation treatments were evaluated on ‘Sovereign Coronation’ (Vitis labruscana) table grapes at two vineyard sites in Ontario, Canada in 2003 to 2005 to assess the usefulness of the Food and Agriculture Organization of the United Nations Penman-Monteith equation for predicting vine irrigation needs. Data (relative humidity, wind speed, solar radiation, and temperature) for calculating reference evapotranspiration (ETo) were downloaded from the Ontario Weather Network. The five irrigation treatments were nonirrigated control plus four based on combinations of one of two ETo values [100% (ET100) or 150% (ET150)] and two crop coefficients [Kc (fixed at 0.75 or 0.5–0.8 based upon increasing canopy volume)] used to calculate the required irrigation water volume. Transpiration (Ts), leaf water potential (ψ), and soil moisture data were collected in all three seasons. Yield components data were collected and berries were analyzed for soluble solids, pH, titratable acidity (TA), anthocyanins, methyl anthranilate (MA), and total volatile esters (TVE). Irrigation typically increased Ts rate and soil moisture; the nonirrigated treatment showed consistently lower Ts and soil moisture over the three seasons. Irrigation also increased leaf ψ, which was lower throughout the three seasons for nonirrigated vines. Irrigation additionally increased yield and its various components (clusters per vine, cluster weight, and berries per cluster) in 2005. Berry weights were higher for irrigated treatments at both sites, and were consistently the main variable leading to yield increases. Soluble solids was highest for the Kc = 0.75 treatments. pH, TA, anthocyanins, and phenols were highest in nonirrigated treatments in 2003 and 2004, but were highest in irrigated treatments in 2005. MA and TVE were highest in the ET150 treatments. The use of irrigation was effective in reducing water stress and for improving yield and fruit composition of ‘Sovereign Coronation’ table grapes in the Niagara region of Ontario. The ET150 treatments were particularly beneficial. Soil and vine water status measurements indicated that irrigation was required for Summer 2003 and 2005 due to dry conditions.

Effect of water stress on yield and evapotranspiration of sunflower

SUMMARY An experiment was conducted at Rimski Sancevi Experiment Field of Institute of Field and Vegetable Crops in Novi Sad during 2000 - 2005. The soil in the experimental plot was calcareous chernozem on loess terrace. Using the yield response factor (ky), the study investigated how sunflower yield and evapotranspiration were affected by deficit of available soil water during the growing season. The experiment consisted of an irrigated treatment (T1), in which irrigation was used when soil moisture levels dropped to 60-65% of FC (field capacity), and a nonirrigated control treatment (T0). The sunflower hybrid used in the study was NS-H-111. On average, no significant differences in yield level were observed between T1 (3.79 t ha -1 ) and T0 (3.75 t ha -1 ) treatments. Seasonal evapotranspiration (ETm) obtained in T1 treatment was in the 402-479 mm range. The yield response factor (ky) was obtained as 0.20 for total growing season and 0.27, 0.31 and 0.48 for vegetative, flowering and yield formation period, respectively. Period from flowering to maturity was the most sensitive towards water deficiency.

Long-term impacts of pasture irrigation with treated sewage effluent on shallow groundwater quality

The study investigated the effects of 26 years of effluent irrigation on chemical and bacteriological quality of shallow (<3.0 m) groundwater. Annual loading rates for N and P exceeded pasture requirements, while trace metals were either lower or higher than guideline limits. Effluent irrigation removed TN (44-71%), TP (80%), Cr (96%) and coliform bacteria (87-99.9%) while Zn, Cu and Cd removal was negligible probably due to their enhanced mobility. Analysis of groundwater samples from effluent-irrigated and non-irrigated control sites showed that effluent irrigation increased the levels of all measured parameters compared to the control. Average groundwater quality parameters from effluent-irrigated sites compared to the control were: pH (6.1 vs. 5.7), EC (0.71 vs. 0.53 dS m(-1)), concentrations (mg L(-1)) for TP (2.3 vs. 0.3), DP (1.0 vs. 0.1), TN (15.1 vs. 2.5), NH(4)-N (2.6 vs. 0.5), NO(3)-N (4.1 vs. 1.3), Zn (0.4 vs. 0.05), Cu (0.13 vs. 0.02), Cd (0.05 vs. 0.01) and Cr (0.06 vs. 0.03). Across effluent-irrigated sites, FC and TC were 25 and 288 cfu/100 ml, respectively, versus nil for the control. Overall, effluent irrigation led to groundwater contamination by N, P, trace metals and coliform bacteria, which could threaten the long-term sustainability of the practice.

Effect of Long-term Wastewater Application on Physical Soil Properties

To evaluate the long-term effect of wastewater application on soil physical properties, two treatment sites, close to Taupo and Levin, New Zealand, and non-irrigated control sites were compared. The soil at Taupo was a silt loam and has received wastewater application for 12 years. The soil at Levin is a sand, and has been wastewater irrigated for 22 years. The disposal blocks at both sites had a higher pH, a higher organic matter (OM) content, a lower bulk density, and thus higher total porosity, but a lower macroporosity than the control sites. The disposal block at the Levin site showed a higher hydrophobicity than the control block, which coincided with the higher soil carbon. In contrast, the Taupo soil showed a higher hydrophobicity at the control site, the site with the lower OM content. Long-term wastewater irrigation resulted in a higher aggregate stability, and changes of the total porosity following stress application were lower, suggesting higher internal soil strength. The hydraulic conductivity close to saturation was also higher in the disposal blocks. The soil mechanical strength, as determined by the precompression stress value was, however, slightly lower in the disposal blocks and not correlated with the aggregate stability.

Potato yield and metabolic profiling under conventional and organic farming

Consumers interest for organic agriculture and environmental-friendly agricultural products is increasing. Nevertheless, cultivation protocols in organic farming are not sufficiently standardized to guarantee product quality stability, a parameter which is critical for further expansion of this niche market. Variable responses in terms of quality and quantity of the harvested product often arise from complex interactions between agronomic and environmental factors. Here we report on the effects of different levels of nitrogen fertilization (0, 50, 150, 200 kg N ha −1) and irrigation regime (50% and 100% replenishment of the evaporation determined using a Class A pan, plus a non-irrigated control) on yield and accumulation of primary metabolites of two potato cultivars (Agria and Merit) grown under conventional and organic farming systems. Organic farming caused a 25% marketable yield reduction with a higher percentage of large tubers under conventional farming, whereas irrigation increased the marketable yield and the percentage of large tubers. Nitrogen fertilization affected the marketable yield and significantly interacted with the irrigation regime in modifying potato yield and quality. Farming protocol, cultivar, irrigation and nitrogen fertilization all affected both amino acid contents and composition with a significant decrease of most essential amino acids in coincidence with highest nitrogen levels. An increased water availability caused an accumulation of reducing sugars in potato tubers only in organic farming, whereas such accumulation was not observed under conventional farming. These results indicate that cultivar-specific genetic determinants and cultivation factors, including the farming system, may strongly and specifically interact to affect important quality parameters of potato tubers. This should be considered to improve quality standards in organic farming.

Sugarbeet seed’s yield and quality as affected by irrigation

Irrigation to the sugar-beet seed crop is a common practice since many years in Emilia Romagna region, even though information on the most suitable ways to irrigate is very limited. The aim of this three-year long experimentation was to evaluate the influence of timing and number of irrigation treatments on seed yield and quality. Treatments at the onset, at full, and at the end of flowering, wit all their possible combinations were compared among themselves and with the non-irrigated control. During the second and third years the water content of the soil was monitored weekly, starting from just before the first treatment to harvest. These measurements indicate that the upper layers (0-20 cm), which are more subjected to evapotranspiration, are more affected by irrigations than the deeper layers (20-40). The effectiveness of irrigation treatments on seed yield was tightly dependent in the distribution of precipitations. The treatments applied in full or late flowering, both separately or together, determined significant increases in yield and in the percentage of seed balls with a diameter higher than 4.0 mm, whereas those at the beginning of flowering did not produced any improvements. No significant effects of the different treatments on 1000-seed weight and germinability were observed, except for a slightly negative influence of irrigations applied at the end of flowering.When all the traits were considered, an overall moderate correlation was detected between seed yield and quality.

Soil Water Dynamics and Growth of Street and Park Trees

Soil water dynamics were studied in 100 street tree planting pits and in the soil surrounding five park trees. Volumetric soil water content and stem cross-sectional area increment were measured on both park and street trees. Different levels of irrigation were implemented on the 100 street trees. Winter assessments of soil wetness at field capacity showed that the water retention capacity was lower in street planting pits than in the park soil attributable to the rather coarse substrate used in the planting pits. High variability among street tree planting pits in regard to water retention capacity was determined and may be related to poor standardization of the substrates, but may also be affected by varying drainage conditions. The rate of water loss in the street tree planting pits was very high immediately after rainfall or irrigation and decreased exponentially during the first 10 days after water input. This was attributed to rapid drainage. The water loss rate in the park soil was on average slightly higher than in the nonirrigated control street pits but showed a more linear decrease over time. We concluded that the water loss in the park soil during summer was primarily driven by transpiration of trees (above 10 L/day [2.6 gal/day]), which complies with common Danish forest experience. The relationship between water loss and tree growth was reversed in the street tree planting pits. The street trees did consume water for growth, but growth and transpiration of the street trees were not a noticeably driving mechanism in the planting pit hydrology. The large variation in street tree increment is attributed to the variation among street planting pits in their ability to retain water. The faster the water loss rate, the slower the tree growth. Irrigation did not prevent final depletion of the soil water resource in planting pits, but irrigation elevated the water content for limited periods during the growing season and thereby enhanced tree growth. Besides the obvious possibilities for improved water balance by horizontal and vertical expansion of the rooting zone, we also suggest improving the water retention capacity of planting pit soil by adding clay nodules. Options for continuous monitoring of tree vitality and soil water content to optimize maintenance are discussed.

Influence of Irrigation on Vine Performance, Fruit Composition, and Wine Quality of Chardonnay in a Cool, Humid Climate

Five irrigation treatments (nonirrigated control; irrigation cut-offs imposed postbloom, lag phase, and veraison; and full season irrigation) were evaluated in an Ontario Chardonnay vineyard over a 4-yr period. The modified FAO Penman-Monteith evapotranspiration formula was used to calculate water budgets and schedule irrigations. Transpiration rate, midday leaf water potential, and soil moisture data suggested that the control and early cut-off treatments were frequently under low water status, despite ample precipitation in two of four seasons. Full season irrigation increased yield by 18% (2001) and 19% (2002) over the control due primarily to increased berry weight. Soluble solids were increased by irrigation, and full season irrigation showed similar or higher Brix than all other treatments in two of four years. Berry titratable acidity and pH also fell within acceptable levels for all five treatments, although titratable acidity was slightly higher in irrigated treatments in two of four years. Wines made from irrigated grapes had greater intensities of apple, citrus, and floral aromas and flavors, and less earthy aroma and flavor. These results strongly suggest that irrigation is a viable option for winegrape vineyards in Ontario and the northeast United States, with potential for simultaneous increases in yield, soluble solids, and desirable wine sensory attributes.